The purpose of the present study was to determine an optimal exercise intensity to enhance peripheral circulation during exercise. The training consested of an exhausting dynamic handgrip at a frequency of 60% contractions/min, conducted 5 days/week for 6 weeks. The load applied corresponded to 20% and 30% MVC.The results obtained were summarized as follows ; 1. Eighteen women aged 18-19 yrs were divided into 2 groups ; training group (T group) and control group (C group). After training at 30% MVC, the number of contractions in T group increased significantly. The blood flow immediately after exhausting exercise did not change significantly. In C group, no significant changes in the circulatory parameters were observed.2. The right forearms of 5 women participated in the training at 20% MVC and the left forearms served as control. The number of contractions increased significantly after training, accompanied by augmented peak blood flow in the trained forearm from 24.3(〕SY.+-.〔)3.1 ml/100ml/min (pre-training) to 31.1(〕SY.+-.〔)3.2 ml/100ml/min (post-training)3. Theses results suggested that the training at 30% MVC could improve musclar endurance without increase in blood supply, while the 20% MVC training would contibute to improve oxygen transport capacity.